1. Field of the Invention
The present invention relates to a high-pressure fuel supply circuit, and more particularly to a high-pressure fuel supply circuit that is capable of cutting off inflow of air by a selective check valve provided therein.
2. Description of the Related Art
Generally, a fuel pump of a gasoline direct injection (GDI) engine pressurizes a fuel supplied from a fuel tank through a fuel line and injects it into a combustion chamber such that a predetermined amount of the fuel is supplied uniformly to each cylinder with desirable fuel injection timing according to a change of engine load or engine speed.
That is, foreign materials mixed in the fuel are filtered by a fuel filter, and the filtered fuel is drawn and is injected to the combustion chamber by the injector.
In this case, since the distance between a fuel tank of a vehicle provided with the GDI engine and the injector is too far, most vehicles are provided with an additional priming pump so as to remove air from the fuel line.
Air in the fuel line causes problems in fuel supply during start-up, and an error occurs in fuel pressure control and injection timing that causes deterioration of startability and drivability. Therefore, it is required to exhaust air from the fuel.
In addition, since air is compressible, it causes a sponge phenomenon that causes deterioration of high-pressure fuel injection and forming of a proper pressure.
As can be seen from the foregoing, when the air is compressed the pressure thereof becomes low, and thereby deterioration of fuel injection and the sponge phenomenon occur.
When using a vehicle as mentioned above, deterioration of starting and acceleration occurs, and the problem is more severe in a GDI engine in which gasoline is injected at a higher pressure than in a standard gasoline engine.
Meanwhile, since the GDI engine vehicle according to the prior art provided with the priming pump should be controlled manually, a driver should directly detect whether air flows in the line between the fuel tank and the injector, and thereby it is limited for a driver to detect the problem of the vehicle precisely.
Further, since the priming pump operates in such a manner that a cylinder and a priming pump are assembled by a screw, air-tightness or performance of pumping is not reliable.
Therefore, the driver should directly operate the priming pump, which causes inconvenience to a driver, and when air flows in the line between the fuel tank and the injection pump and the driver does not realize this so does not operate the priming pump manually, the deterioration of starting and acceleration occurs.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.